Plug and spring-jack switch.



PATENTED MAY 24, 1904.

1:". R.. MoBERTY. PLUG AND SPRING JACK SWITCH.

APPLICATION FILED JAN. 6. 1900.

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N0 MODEL.

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No. 760,549. PATENTED MAY 24:, 1904. P. R. MQBERTY.

PLUG AND SPRING JAGK SWITCH.

APPLICATION FILED JAN. 6.1900.

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UNITED STATES Patented May 24, 1904.

PATENT OEEICE.

FRANK R. MGBERTY, OF EVANSTON, ILLINOIS, ASSIGNOR TO THE WESTERNELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORA' ION OF ILLI- NOIS.

PLUG AND SPRING-JACK SWITCH.

SPECIFICATION forming part of Letters Patent N0. 760,549, dated May 24,1904. Application filed January 6, 1900. Serial No. 538. (No model.)

To all whom it may concern Be it known that I, FRANK R. IVloBERtrY, acitizen of the United States, residing at Evanston, in the county ofCook and State of Illinois, have invented a certain new and usefulImprovement in Plug and Spring-Jack Switches, of which the following isa full, clear, concise, and exact description.

My invention relates to plug and spring- IO jack switches such as areused in switchboards of telephone-exchanges; and its object is toprovide an improved switching mechanism which will be compact, durable,and reli ableand in which the several steps in the insertion of the plugmay be accomplished without liability of false contacts.

My invention will be described by reference to the accompanyingdrawings, illustrating the preferred embodiment thereof, and the parts,improvements, or combinations considered to be novel will be pointed outin the appended claims.

Figure 1 is an elevation of a block of ten spring-jacks of my invention.Fig. 2 is a 5 plan view thereof, partially in section. Figs. 3, 4:, and5 are sections on line 6 6 of Fig. 2, the plug being shown in itsseveral stages of insertion into the spring-jack. Fig. 6 is a detailview illustrating the manner of assem- 3 bling the different parts of astrip of springjaeks.

The long and the short line-springs a b are mounted one above the otherin a rear insulating-strip 0, their projecting ends a and 6" be- 3 5 ingformed to receive the wires going to the substations or other parts ofthe board, and the contactmints thereof are bent to iit into theirrespective places on the plug and hold the same in position untilforcibly withdrawn.

4 A strip of hard rubber (Z, extending for some distance between the twosprings a 6, tends to keep them apart while the plug is being inserted.A stop 0, which preferably has very little elasticity, is associatedwith the short line-spring 7) and tends to hold both the long and theshort line-springs in position to be most easily engaged by theirrespective plugcontacts. This stop a is preferably mounted in the block0 directly upon the short linespring band need not be insulatedtherefrom, as it has no electrical connection with any of the lines, itsrigidity being employed to better advantages when associated'direetlywith the spring. I prefer to use German silver in the construction ofthe line-springs.

In order that the frame of the springjacks may be made as thin aspossible, the shorter line-spring b is mounted nearly in alinement withthe central axis of the thimble g of the jack, and in order that it mayiit over the rounded head of the plug said line-spring is arched orprovided with a double curve, as

shown most clearly in Figs. 3, 4, and 5. The longer line-spring is alsoarched or provided With an outward curve a to clear the arched portionof the inner spring and prevent any possible contact between the twosprings while the plug is being inserted. By virtue of these peculiarbends in the springs the strip of spring-jacks can be made thinner thanwould otherwise be possible.

The thinible g of the jack, which is embedded in a block of insulatingmaterialf', has an extension it placed at the side of the line-springs aZ) and bent at its extremity, so as to pass through the block 0 in aplane parallel tothe line-springs, but in no electrical connectiontherewith. It will at once be seen that this method of arranging theextension of the thimble will prevent any liability of contact beingmade between it and either of the springs or with the plug when insertedon account of accidental bending, as it is in such a position that itcannot be reached by anything which would tend to injure its shape.

The insulating-support c for the line-springs and the extensions ii ofthe test-thin1bles are composed of strips of hard rubber, between whichthe metal parts are inserted, the lower insulating-strip preferablyhaving transverse grooves Z l therein adapted to receive the linespringsand the other insulating-strips serving to separate the metal parts fromone another. The several parts are held firmly together by screw-boltsa, forming practically a single strip or block which supports andinallow the curve a of the long line-spring a free movement during theinsertion of the plug.

The construction of spring-jacks herein described is especiallyadvantageous in that it admits of a very compact arrangement of theparts, wherebyalarge number of spring-jacks may be assembled in smallcompass.

The plug which forms a part of my invention differs from those ingeneral use in several particulars, the most important features of whichI will set forth. The tip m is preferably made of aluminium-bronzecomposition and is connected to the line-wires by means of a narrow rod'm, passing within the plug. The ring contact a is composed of a smallmetal tube surrounding the rod m, but insulated therefrom, and is itselfembedded in insulating material, separating it from the shank 0 of theplug. A metal ring or shoulder p is supplied between the tip and ringcontacts, embedded in hard rubber, which is adapted to take up the wearthat would cut away the soft insulating material. The diameter of thisshoulder is the same as that of the shank of the plug, and each isadapted to fit snugly in the thimble of the jack, While notbeing toolarge to prevent entering freely. A special feature of my invention isthe relative diameters of the tip and the shoulder insulated there- Ifrom, the tip being of a considerably smaller diameter, the especialadvantage of which will be explained shortly. The ring contact is alsoof a relatively small diameter. The rubber insulation surrounding thering contact is enlarged about its outward extremity to form theshoulder o of the same diameter as the shank of the plug, which preventsthe long spring from making contact between the ring and shank contactsof the plug and is of great importance in preventing the tip and shankfrom making connection at the same time with the thimble of thespring-jack, as will be described. The shank 0 is enlarged to form ashoulder 0, which is adapted to engage the outward extremity of thethimble of the jack, and thereby prevent the plug from entering too farinto the springjack. The heel of the plug is enveloped by a layer ofinsulation 8, which serves to protect the plug from objectionablecontacts.

Havingthus described the features and construction of my invention, Iwill proceed to point out in detail how it will eliminate all chance ofundesirable contacts in the opera- I tion of insertion and removal ofthe plug from the spring-jack.

The principal difiiculty in the past has been met at the first stage ofinserting a plug into the jack of a line. The tip of the plug is firsttouched to the thimble of the jack to find whether or not the calledline is busy, and if the line was not in use the plug was pushed intothe jack. Upon inserting my plug into its spring-jack the tip makescontact with the thimble, as usual, and when the plug is insertedfarther, so that the shoulder 12 is also inserted, the tip may stillmake contact if the plug is at an angle. When the hard-rubber shoulder0' comes into engagement with the outer end of the thimble, the metaland hardrubber shoulders being, as stated, of such a diameter as to fitsnugly into the thimble, the axis of the plug is thrown in direct linewith the axis of the thimble of the spring-jack, and

thus forces the tip exactly in the central part of the thimble. Theshank of the plug now coming into contact with the outer extremity ofthe thimble increases the bearing-surface and does not permit of anyrocking which would allow the tip to make contact.

I have done away with the other objections which were previouslymentioned by making the tip of my plug of a shorter length than thedistance between the contact-points of the two line-springs or thedistancebetween the contact-point of the long line-springand the thimbleof the spring-jack. It will also be seen by referring to Fig. 4 that themetal shoulder 11 will prevent the tip from bridging the longline-spring and the thimble and in addition will prevent the tip andring contacts of a plug from being short-circuited by the metallic partsof a spring-jack during the insertion of the plug therein.

Having thus described my invention, I claim as new, and desire to secureby Letters Patent, the following:

1. In a spring-jack, the combination with a flexible line-spring, a flatand rigid metal stop therefor in a plane parallel to the line-spring andin contact therewith, a metal base-plate and strips of insulatingmaterial thereon having transverse grooves in which the said spring andstop lie, and means for securing the stop, spring and insulating-stripsto the base-plate, as described.

2. In a spring-jack, the combination with two line-springs of differentlengths and an intervening insulating-piece, of a fiat metal strip of alength nearly equal to the short linespring and lying in contacttherewith beneath the spring, and an insulating-support for saidline-springs and strip at the rear of the jack, substantially as setforth.

3. A strip of spring-jacks comprising a supporting-plate with front andrear insulatingstrips carried thereby, thimbles g in transverse holes inthe front insulating-strip, long and short line-springs insulated fromone another and supported by the rear strip, the shorter line-spring ofeachspring-j ack being mounted substantially in alinement with the axisof the thimble and being curved at its end to fit over the rounded tipof an inserted plug, said longer line-spring being arched over thecurved portion of the short spring, the arched portions of saidline-springs lying at the side of the axis of the thimble toward saidsupporting web or plate in, said plate being cut away to clear thearched portion of said longer line-spring.

4,. In a switchboard-plug, the combination with the tip on and thecontact ring or sleeve a, of a metal insulated ring between the tip andsleeve to take the wear, as described.

5. The combination with a spring-jack having a long and a shortline-spring and a metallic thimble, of a plug adapted for insertion inthe spring- 'jack, tip, ring and shank contacts m a 0 for the plug, saidtip and ring contacts being of smaller diameter than the shank, and aring 7) on the plug between the tip and ring contacts, of substantiallythe diameter of the shank, and fitting snugly into the thimble of thejack, whereby short circuits between the contacts of the plug while itis being inserted in the jack are prevented, substantially as described.

6. The combination in a strip of spring jacks, ofa metal base-plate anda strip of insulating material mounted thereon near each edge thereof,metal thimbles in transverse perforations of one insulating-strip, eachof said. thimbles having an extension which is transverse to the stripof jacks in a plane perpendicular to the base-plate between the stripsand in a plane parallel with the base-plate where it passes the otherstrip of insulating material, two line-springs with an interveningtongue of insulating material, and a flat metal stop beneath one of theline-springs of each swing-jack in electrical connection therewith, saidstep, line-springs and extension of the thimble lying parallel in thetransverse grooves of said other strip of insulating material, and meansfor securing the springs and extension in the groove, as described.

7. A switchboard-plug comprising tip, ring and shank contactsdistributed at intervals along the axis of the plug and insulated fromone another, said tip and ring contacts being of smaller diameter thanthe shank, and a metal collar between the tip and ring contacts andinsulated therefrom, said collar being of substantially the same outsidediameter as the shank.

8. In a strip of spring-jacks, the combina nation with front and rearinsulatirig-strips, metal thimbles inserted transversely in the frontstrip, line-springs supported in the rear strip-and extending forward inalinement with said thimbles, and extension-tongues 71, for saidthimbles leading from the side thereof and bent at a point intermediateof the front and rear strips to pass through the rear strip above and ina plane parallel to the linesprings, substantially as set forth.

9. A switchboard-plug having tip and ring contacts distributed atintervals along the axis of the plug, and insulated from one another,and an insulated metal ring adapted to take the wear lying between saidcontacts, said ring being of greater diameter than either of saidcontacts; whereby short-circuiting of the contacts is prevented.

10. The combination with a spring 'iack having two contact-springs, aplug and two contact portions carried thereby adapted to engage saidsprings, respectively, and an enlarged insulated metallic collar betweenthe contact portions of the plug, said collar having no electricalconnection with said springjaek whenthe plug is inserted.

11. The combination with a spring-jack comprising a test-thimble and twocontact-springs having contact portions at different distances from therear of said thimble, of a plug hav ing tip, ring and shank contactsadapted to engage with said eontact-sprin gs and said testthimblerespectively, and an insulated metal collar between the tip and ringcontacts of the plug and of greater diameter than either, said collarhaving no electrical connection with the spring-jack when the plug isinserted.

In witness whereof I. hereunto subscribe my name this 17th day ofNovember, 'A. D. 1899.

FRANK R. M GBERTY.

Witnesses:

GEORGE P. BARTON, J. WV. SKINKLE.

